ATLAS

Abstract:

In a bubble chamber experiment with BEBC the spin alignment parameter η= 1 2 (2ρ{variant}00 - ρ{variant}11 - ρ{variant}-1-1) is measured for ρ{variant}0 mesons produced in deep inelastic charged-current antineutrino and neutrono interactions on neon. In the current fragmentation region η is found to be ηv=0.48±0.27 (stat.)±0.15 (syst.) for vNe and ηv=0.12±0.20 (stat.)±0.10 (syst.) for vNe interactions. © 1987.

Abstract:

A study has been made of the decays W → ev and Z → e+e-, using the UA2 detector at the CERN p̄p Collider. The data correspond to an integrated luminosity of 142 nb-1 at a centre-of-mass collision energy √s=546 GeV, and 768 nb-1 at √s=630 GeV. Measurements of the standard model parameters from samples of 251 W decay and 39 Z decay candidates are compared with expectations of the standard electroweak model. © 1987.

Abstract:

The invariant mass distribution of jet pairs observed in the UA2 central calorimeter is examined in the search for an excess of events in the region of the W± and Z bosons, which would reveal their decays into quark-antiquark pairs. We give a detailed account of the methods of analysis used to optimize the mass resolution achieving ≅±10%. A structure is observed at the level of ≅ 3 standard deviations in the mass region of W± and Z with shape and position consistent with expectation from their qq̄decays. It contains 632 ± 190 events, 1.4 standard deviations above the standard model prediction of 340 ± 80 events. © 1987.